Label switching in fibre channel networks

ABSTRACT

Methods and apparatus are provided for label switched routing in fibre channel networks. Techniques are provided for implementing label switching based on particular characteristics of fibre channel networks. By using label switching, mechanisms such as traffic engineering, security, and tunneling through networks that do not support fibre channel frames can be implemented.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to concurrently filed U.S. patentapplication Ser. No. 10/114,568 by Maurilio Cometto and Scott S. Lee andtitled Methods and Apparatus For Fibre Channel Frame Delivery, theentirety of which is incorporated by reference for all purposes. Thepresent application is also related to U.S. patent application Ser. No.10/034,160 by Tom Edsall, Dinesh Dutt, and Silvano Gai and titledExtended ISL Header as of filing on Dec. 26, 2001, the entirety of whichis incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fibre channel networks. Morespecifically, the present invention relates to methods and apparatus forlabel switching in fibre channel networks.

2. Description of Related Art

In connectionless networks such as packet-switched networks, labelswitching has conventionally been used to allow for various features.However, it has been difficult to extend label switching into fibrechannel network because of particular characteristics of fibre channelnetworks.

It is therefore desirable to provide methods and apparatus for usinglabel switching in fibre channel networks not only to allow fasteraccess to routing table entries, but also to generally improve fibrechannel frame delivery.

SUMMARY OF THE INVENTION

Methods and apparatus are provided for label switched routing in fibrechannel networks. Techniques are provided for implementing labelswitching based on particular characteristics of fibre channel networks.By using label switching, mechanisms such as traffic engineering,security, and tunneling through networks that do not support fibrechannel frames can be implemented.

According to various embodiments, a method for routing fibre channelframes in a fibre channel fabric is provided. The method includesreceiving a fibre channel frame having a first stack of labels at afibre channel switch and referencing an entry in a label informationbase at the fibre channel switch based on the stack of incoming labels.The method also includes removing the first stack of labels from thefibre channel frame and forwarding the fibre channel frame.

According to various embodiments, a method for tunneling fibre channelframes is provided. The method includes receiving a fibre channel frameat a gateway between a first network supporting fibre channel and asecond network not supporting fibre channel. The method also includesidentifying an incoming label associated with the fibre channel frame,the incoming label determined using fibre channel routing mechanisms.The incoming label associated with the fibre channel frame is swappedwith an outgoing label, the outgoing label determined by referencing anentry in the label information base associated with the gateway. Themethod also includes inserting additional labels to the fibre channelframe, wherein the additional labels are determined using non-fibrechannel routing mechanisms. The additional labels used to forward theframe in the second network.

According to still other embodiments, a method for configuring a tunnelin a fibre channel network is provided. The method includes receivingaugmented link state update information at an ingress fibre channellabel switching router, selecting a route from the ingress fibre channellabel switching router through a plurality of core fibre channel labelswitching routers to an egress fibre channel label switching routerusing the augmented link state update information, and generating atunnel setup message having information identifying the plurality ofcore fibre channel label switching routers.

According to other embodiments, an ingress fibre channel label switchingrouter is provided. The ingress fibre channel label switching routerincludes a memory and a processor. The processor is operable to receiveaugmented link state update information, select a route through aplurality of core fibre channel label switching routers to an egressfibre channel label switching router using the augmented link stateupdate information, and generate a tunnel setup message havinginformation identifying the plurality of core fibre channel labelswitching routers.

These and other features and advantages of the present invention will bepresented in more detail in the following specification of the inventionand the accompanying figures, which illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, whichare illustrative of specific embodiments of the present invention.

FIG. 1 is a diagrammatic representation of a network that can use thetechniques of the present invention.

FIG. 2 is a diagrammatic representation of a fibre channel framesupporting label switching.

FIG. 3 is a diagrammatic representation of a routing table in a labelswitching router.

FIG. 4A is a flow process diagram showing generation of a tunnel at aningress label switching router.

FIG. 4B is a flow process diagram showing generation of a tunnel at acore label switching router.

FIG. 4C is a flow process diagram showing generation of a tunnel at anegress label switching router.

FIG. 5A is a flow process diagram showing ingress label switching routeroperations.

FIG. 5B is a flow process diagram showing core label switching routeroperations.

FIG. 5C is a flow process diagram showing egress label switching routeroperations.

FIG. 6 is a diagrammatic representation showing tunneling using labelswitching.

FIG. 7 is a diagrammatic representation showing traffic engineeringusing label switching.

FIG. 8 is a diagrammatic representation of one example of a fibrechannel network that supports in order delivery.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to some specific embodiments of theinvention including the best modes contemplated by the inventors forcarrying out the invention. Examples of these specific embodiments areillustrated in the accompanying drawings. While the invention isdescribed in conjunction with these specific embodiments, it will beunderstood that it is not intended to limit the invention to thedescribed embodiments. On the contrary, it is intended to coveralternatives, modifications, and equivalents as may be included withinthe spirit and scope of the invention as defined by the appended claims.

Methods and apparatus of the present invention provide for labelswitching of fibre channel frames. According to various embodiments,fibre channel frames include label stacks that allow fibre channelframes to be tunneled through networks that do not support fibre channelframes and rerouted around downed links. Fibre channel frames can alsobe delivered in order using label switching.

In a typical connectionless fibre channel network such as a class two orclass three fibre channel network, a packet travels from one networkentity to the next network entity based on an independent forwardingdecision at each switch. The next hop for a frame is determined based oninformation including a destination address in the frame header. In alabel switching domain, however, label switching routers make forwardingdecisions based not on the destination address in the frame header butinstead based on label information associated with a frame. No analysisof the packet header or frame header is needed at each hop.

Instead, the label in the packet or frame is used to index an entry in aforwarding table that contains the next hop information and a set of oneor more new labels to be used as the packet is forwarded. The next hopcan then use a new label to forward the frame. Although label switchingwas originally developed in TCP/IP networks to simplify access torouting table entries, the techniques of the present inventioncontemplate using label switching in fibre channel networks to enablefeatures such has traffic engineering, tunneling, and in order deliveryin addition to facilitating routing table access. Label switching asMultiprotocol Label Switching (MPLS) for IP networks is described in RFC3031.

Several obstacles prevent the implementation of label switching in fibrechannel networks. One obstacle is that some fibre channel devicesrequire that fibre channel frames be delivered in order. Label switchingused in TCP/IP networks often can deliver packets out of order. However,network entities in TCP/IP networks can handle out of order packets.Destination nodes typically reorder packets received out of sequence.Some fibre channel devices, however, can not handle out of order frames.Furthermore, fibre channel frames do not have a mechanism for carryinglabels.

FIG. 1 is a diagrammatic representation of the network that can use thetechniques of the present invention. According to various embodiments, alabel switching domain 131 includes edge label switching routers 111 and121, and core label switching routers 113, 115, 117, and 119. Aninterconnected set of network entities that support label switching forforwarding frames is referred to herein as a label switching domain. Aswitch that is outside the label switching domain 131 can useconventional techniques for accessing routing table entries andforwarding frames. In one example, a switch 101 may send a frame withouta label to a label switching router 111. Without label switching, alabel switching router 111 typically uses the destination addressprovided in the frame to identify a next hop for the frame. The next hopthen similarly accesses the destination address and determine thesubsequent hop based on the destination address to continue forwardingthe frame until the frame finally reaches the destination.

Using label switching however, an edge label switching router 111 adds alabel to the frame from switch 101. The label can then be used at asubsequent hop, core label switching router 113, to access a routingtable to again determine where to transmit the frame. Instead of usingthe destination address at router 113, a label is used at router 113 toaccess a forwarding entry. When a label switching router is connected toa label unaware switch, the label switching router is referred to hereinas an edge label switching router. Any device that does not support theuse of labels for forwarding decisions is referred to herein as a labelunaware switch. The edge label switching router can be an ingress labelswitching router when it handles traffic entering into the labelswitching domain. The edge label switching router can be an egress labelswitching router when it handles traffic leaving the label switchingdomain. In one example where a frame is transmitted from switch 101 toswitch 105, edge label switching router 111 would be the ingress labelswitching router while edge label switching router 121 would be theegress label switching router. It should be noted that some labelswitching routers could be core and edge label switching routers.

The label switching routers connected to other label switching enabledrouters are referred to herein as core label switching routers.According to various embodiments, all the incoming packets or framesreceived at core label switching routers include labels. Consequently,core label switching routers only need to look at the incoming label inorder to make the forwarding decision. According to other embodiments,some incoming packets or frames received at a core label switchingrouter do not include labels. Consequently, some packets and frames areswitched without the use of labels.

It should be noted that a switch can be both a core label switchingrouter and an edge label switching router. Edge label switching router121 is connected to label switching router 117 and 119 while it isconnected to label unaware router 105 and label unaware storage device107.

FIG. 2 is a diagrammatic representation of a frame that can include alabel for label switching. According to various embodiments, the labelswitching header 207 is located between the Extended Inter-switch Links(EISL) header 203 and the fibre channel header 211. EISL is described inapplication Ser. No. 10/034,160 titled Methods And Apparatus ForEncapsulating A Frame For Transmission In A Storage Area Network byThomas J. Edsall, Dinesh G. Dutt, and Silvano Gai. The EISL header 203includes a label switching indicator 205 that provides information onwhether a label is provided in the frame.

According to specific embodiments, the label switching header 207includes a stack of 32-bit words. Each label includes a 20-bit label foraccessing an entry in a routing table, a 3-bit experimental field, a1-bit EOS field, and an 8-bit time-to-live (TTL) field. The label valueis used at a label switching router to determine the next hop, the stackbit is used to indicate that the bottom of a stack of labels has beenreached. It should be noted that the label switching header can includemore than one label. The time-to-live field is decremented at each hoplike the time-to-live field in a conventional TCP/IP packet.

Although the label switching header described above is included betweenan EISL header and a fibre channel header 207, it should be noted that alabel switching header can be included in a variety of different fieldsassociated with the frame. For example, a label switching header can beincluded in a frame that does not include an EISL header 203. In thisexample, the label switching indicator can be provided in a fibrechannel header 211, and label switching information can be included inthe fibre channel payload. However, it should be noted that a labelswitching indicator and label switching information can instead beincluded in an extended fibre channel header.

FIG. 3 is a diagrammatic representation of a label information base(LIB). In the example shown, label switching information and routingtable information is maintained in the same entity. However, a routingtable and label switching information can be maintained in separateentities. An entity including label switching information is referred toherein as a label information base (LIB). Some LIB entities may includeonly a label information base and no routing table information.

According to various embodiments, a LIB with routing table informationincludes entries pairing a destination identifier with a next hop. Thatis, the routing tables include a destination identifier column 303 and anext hop column 305. To support label switching, an in or incoming labelcolumn in 301 as well as an out or outgoing label column 307 isincluded. When a frame is received, a label can be used to access anentry in the routing table corresponding to the label in the frame. Inone example, if the label in the frame is 2000, the switch recognizesthat the next hop is switch 43 and the out label should be 3000. In thisexample the destination ID is not used to determine the next hop.

In still other examples, the number of labels to push or pop and adetermination of which labels to insert can be made not only using thedestination ID, but also by policies that are configured in the switch.Some policies include the port number and source and destination pair.It should be noted that routing tables are provided on a per virtualnetwork basis (virtual storage area network (VSAN) or virtual local areanetwork (VLAN)). That is, a routing table is available for eachVSAN/VLAN the label switching router is a part of. A SAN (or a VSAN) maybe a network such as an Infiniband network.

A variety of techniques can be used for generating a LIB. In oneembodiment, a LIB is generated upon the receipt of link state updatepackets under the FSPF protocol. According to other embodiments, a LIBis generated upon receiving augmented link state update packets. Linkstate packets with additional information such as bandwidth availabilityallowing traffic engineering are referred to herein as augmented linkstate update packets. A LIB can be generated periodically or upon theidentification of a change in link state. According to variousembodiments, a newly generated LIB is associated with an incarnationnumber. A combination of all the incarnation numbers in a fibre channelfabric is herein referred to as a topology version number. Using atopology version number can allow for in order delivery of fibre channelframes. Using a topology version number to allow for in order deliveryis described in concurrently filed U.S. patent application Ser. No.10/114,568 by Maurilio Cometto and Scott S. Lee and titled Methods andApparatus For Fibre Channel Frame Delivery, the entirety of which isincorporated by reference for all purposes.

In one embodiment, every time a new routing table is generated at aswitch, the incarnation number is incremented by one. According tovarious embodiments, each label switching router in a fibre channelnetwork not only generates new forwarding routes toward eachdestination, but each label switching router also generates new inlabels different from the previous set of in labels.

The augmented link state update packets can be used to generateconventional routing tables and/or LIBs. Packets received at a labelswitching router can then be routed to a next hop by using labelsinstead of next hop information in a routing table. Alternatively,packets can be forwarded to a next hop using label information in placeof routing table information. Accordingly, label switching routers canbe implemented without routing tables entirely. However, augmented linkstate update packets can also be used to traffic engineer and selectroutes not found using conventional routing table mechanisms. In oneexample, a traffic engineered route may forward a received next packetto a different next hop than a routing table would. Furthermore,augmented link state update packets can be used to specify a route froma source to a destination, whereas routing table information can onlyspecify a next hop.

According to various embodiments, a source label switching routerdetermines the best route to a particular destination. The source thensends a frame explicitly routed to each hop between the source and thedestination on the selected route. A mechanism such as ResourceReservation Protocol (RSVP-TE) can be used to configure routes. RSVP-TEis described in RFC 3209, the entirety of which is incorporated byreference for all purposes.

FIG. 4A is a process flow diagram showing the configuration of routeusing traffic engineering. At 401, the ingress label switching routerdetermines the best route to a destination based on information such asthat provided in the augmented link state update packets. The labelswitching router can also apply other policies for selecting a route. Inone example, the label switching router may attempt to avoid certainlinks. At 403, the ingress label switching router creates a tunnel setup message having information identifying the label switching routers inthe tunnel. Any message for configuring label switching routers on aselected route to forward packets along the selected route is referredto herein as a tunnel setup message. At 405, the ingress label switchingrouter sends the message to the next label switching router in thetunnel. It should be noted that the selected route can be a variety ofdifferent types of routes and tunnels.

In one example, a tunnel established is a virtual private network or VPNtunnel. In another embodiment the tunnel established is an IP tunnel. At407, the ingress label switching router receives a response messagecorresponding to the tunnel set up message sent at 405. According tovarious embodiments, the response to the tunnel set up messageoriginated from the destination. At 409, the label provided in theresponse message is programmed into the LIB.

FIG. 4B is a process flow diagram showing a core label switching routerin a tunnel between the source of the destination. At 421, the corelabel switching router receives a tunnel set up message. At 423, thecore label switching router allocates labels associated with themessage. At 425, the core label switching router forwards the tunnel setup message downstream to the next label switching router in the tunnel.At 427, the core label switching router receives a response messagecorresponding to be tunnel set up message and programs the label intothe LIB at 429. At 431, the core label switching router forwards theresponse upstream to the previous hop in the tunnel.

FIG. 4C is a process flow diagram showing an egress label switchingrouter. At 441, the egress label switching router receives a tunnelsetup message. The destination label switching router generates labelinformation at 443 and sends a response message in the reverse directionalong the same selected route at 445.

Once a tunnel is established, label switching operations may vary basedon whether a label switch is an ingress label switching router, a corelabel switching router, or an egress label switching router. FIG. 5A isa flow process diagram showing one example of label push operations atan ingress label switching router. According to various embodiments, aningress label switching router receives a frame at 501 from a labelunaware node. At 503, the ingress label switching router classifies theframe. At 505, the ingress label switching router identifies the LIBentry corresponding to the classified frame. In one embodiment, an inputor output port identified may be used to select a LIB entry.

At 507, the number of labels and the labels to be pushed onto the labelstack are determined. Any mechanism for holding labels and informationassociated with labels is referred to herein as a label stack. A labelstack can be a stack, a linked list, an array, or any structurecontaining label information. The frame is then modified at 509 toinclude the one or more labels. Modifying the frame can include updatingan EISL header to show that a label is available and placing the labelinformation into a label header.

FIG. 5B is a flow process diagram showing one example of core labelswitching router operations. As noted above, a core label switchingrouter receives frames from a label switching enabled router. At 521, acore label switching router receives a frame. At 523, it is determinedif an LIB entry corresponds to the incoming label associated with theframe. If no entry corresponds, the frame is dropped at 531. Accordingto various embodiments, various error reporting and notificationoperations can also be performed. Although it may be possible to routethe frame based on a routing table next hop, the frame is dropped invarious embodiments in order to limit the chance of a loop in thenetwork. At 525, the labels to be popped, pushed, or swapped aredetermined based on the LIB entry. At 527, the frame is modified to add,remove, or replace label information.

FIG. 5C is a flow process diagram showing one example of egress labelswitching router operations. At 541, the egress label switching routerreceives a frame from a label switching enabled router. It is determinedat 543 whether a label exists in the packet. If no label exists, thepacket is forwarded based on VSAN and destination ID. If a label exists,it is determined whether an LIB entry corresponds to the incoming labelat 545. If no LIB entry corresponds to the label at 545, the frame isdropped at 553. Otherwise, the number of labels to pop is determined at547. The frame is then modified at 549.

FIG. 6 is a diagrammatic representation showing tunneling through aTCP/IP network 655 the does not support fibre channel frames. The labelswitching router 651 provides a frame to gateway 653. The frame includesa first label 665, the fibre channel header 663, and a fibre channelpayload 661. According to various embodiments, the frame may not includea first label 665. The gateway 653 recognizes that it is about toforward a labeled fibre channel frame through a TCP/IP network 655 thatdoes not support fibre channel frames. The fibre channel gateway 653uses a frame including a top label 675, an ethernet header 677, and asecond label 673. The top label is used to pass traffic from gateway 653to gateway 657 and the bottom label is used to forward the traffic tolabel switching router 659 after the frame reaches gateway 657. The toplabel is determined by forwarding mechanisms in the TCP/IP network 655while the second label is determined by forwarding mechanisms in thefibre channel network.

According to various embodiments, the label switching routers in theTCP/IP network 655 only operate on the topmost label 675 and do not needto access any other labels in the label stack. Accordingly, the entitiesin the TCP/IP network 655 do not need to be aware that the fibre channelframe is being tunneled through the TCP/IP network 655. Instead, theTCP/IP network entities merely forward frames through the network basedon the topmost label.

Unlike conventional TCP/IP networks, fibre channel frames cannot bedelivered out of sequence. Accordingly, a control word 671 including asequence number is included after the label stack, or beneath secondlabel 673, so that the gateway 657 can detect packets arriving out ofsequence. It should be noted that a control word can be included indifferent fields in the fibre channel frame, such as in the fibrechannel header. Any mechanism allowing a fibre channel gateway to detectout of order fibre channel frames after transmission through a non fibrechannel network is referred to herein as a control word.

Also unlike conventional TCP/IP networks, fibre channel network framesare typically not allowed to be dropped for performance reasons.Techniques of the present invention contemplates a gateway 657 detectingthat frames from gateway 653 were dropped and requesting retransmissionin order to provide for efficient frame delivery. It should be notedthat by tunneling using labels, security can also be provided by usingnetwork protocols such as Virtual Private Network or VPN.

FIG. 7 is a diagrammatic representation showing fast link failover,according to various embodiments. A label switching router 783 receivinga frame from label switching router 781 can recognize that a linkbetween router 783 and router 789 is down even though the routing tableinstructs router 783 to forward the frame directly to router 789 throughthe downed link. Instead of waiting for conventional link state updateand link state record techniques to update routing tables, labels can beused to more quickly reroute traffic around the downed link. Accordingto various embodiments, an additional label is pushed onto the labelstack associated with the frame to forward the frame to a labelswitching router 785. The label switching router 785 uses the top labelwith the value of 100 to determine that the frame should be forwarded toa label switching router 787. The top label is then replaced with thevalue of 200. A label switching router 787 then removes the incominglabel 200 and forwards the frame based on the second label with thevalue of 20 to label switching router 789.

The downed link between label switching router 783 and label switchingrouter 789 is bypassed. It should be noted that traffic engineeringusing label switching can be implemented in a variety of differentmanners. In one example, a system administrator can manually set upalternative routes at a label switching router 783. A switch 783 ismanually configured to replace a label stack with a value of 10 with alabel stack with a top label value of 100 and a second label value of20. Link state information can also be passed into the networkautomatically.

Although the techniques of the present invention can be used to providefeatures such as fast failover, explicit source routing, and trafficengineering as noted above, the techniques of the present invention canalso be used to provide for in order delivery.

FIG. 8 is a diagrammatic representation of one example of a fibrechannel network that supports in order delivery. In order delivery isdescribed in concurrently filed U.S. patent application Ser. No.10/114,569 by Maurilio Cometto and Scott S. Lee and titled Methods andApparatus For Fibre Channel Frame Delivery, the entirety of which isincorporated by reference for all purposes.

In addition to containing the destination address, a frame includes as adestination identifier an input label that allows a switch to quicklyaccess an entry in a routing table. For example, a label switchingrouter 804 can receive a frame with a destination of 2 and an in labelof 420. The label switching router 804 can access its routing table 814to recognize that the next hop is label switching router 802 and theoutput should be 220. According to various embodiments, the labelswitching router 804 replaces the frame label value of 420 correspondingto the in label in the routing table with a frame label of 220corresponding to the out label in the routing table 814.

By replacing the label value, the label switching router 804 provideslabel information to the next hop router 802, to allow the labelswitching router 802 to similarly access a routing table entry quickly.It should be noted that although label switching can be provided forfast access of entries in a routing table, label switching can be usedfor a variety of reasons. The techniques of the present inventionprovide that frames can be delivered in order by using labels.

When a label switching router 802 receives a frame from label switchingrouter 804, the label switching router uses the label 220 to access anentry in the routing table 812. Using the in label 220, the labelswitching router 802 recognizes that the frame no longer needs to beforwarded, as the frame has actually arrived at its destination.

As described above, label switching may be performed in a variety ofnetwork devices. According to various embodiments, the switch includes aprocessor, network interfaces, and memory for maintaining LIBs. Avariety of input and output ports, Media Access Control (MAC) blocks,and buffers can also be provided as will be appreciated by one of skillin the art.

In addition, although an exemplary switch is described, theabove-described embodiments may be implemented in a variety of networkdevices (e.g., servers) as well as in a variety of mediums. Forinstance, instructions and data for implementing the above-describedinvention may be stored on a disk drive, a hard drive, a floppy disk, aserver computer, or a remotely networked computer. Accordingly, thepresent embodiments are to be considered as illustrative and notrestrictive, and the invention is not to be limited to the details givenherein, but may be modified within the scope and equivalents of theappended claims.

1. A method comprising: receiving a fibre channel frame having a firststack of labels at a first fibre channel device, the fibre channel framereceived through a tunnel in a Transport Control Protocol/InternetProtocol (TCP/IP) network, wherein a control word in the fibre channelframe is used to reorder frames received out of order at the first fibrechannel switch to provide in order delivery; reordering frames at thefirst fibre channel device; referencing an entry in a label informationbase at the first fibre channel device based on the first stack oflabels; removing the first stack of labels from the fibre channel frame;and forwarding the fibre channel frame in-order to a second fibrechannel device.
 2. The method of claim 1, wherein the fibre channelframe is forwarded substantially without any label information.
 3. Themethod of claim 1, further comprising: inserting a second set of labelsinto the fibre channel frame.
 4. The method of claim 1, wherein thefirst stack of labels comprises of one or more labels.
 5. The method ofclaim 4, wherein the one or more of the labels are associated with oneor more virtual storage area networks.
 6. The method of claim 1, whereinthe first stack of labels is included in the Enhanced Interswitch Links(EISL) header.
 7. The method of claim 1, wherein the first stack oflabels is included in the fibre channel frame header.
 8. An apparatuscomprising: means for receiving a fibre channel frame having a firststack of labels at a first fibre channel device, the fibre channel framereceived through a tunnel in a Transport Control Protocol/InternetProtocol (TCP/IP) network, wherein a control word in the fibre channelframe is used to reorder frames received out of order at the first fibrechannel switch to provide in order delivery; means for reordering framesat the first fibre channel device; means for referencing an entry in alabel information base at the first fibre channel device based on thefirst stack of labels; means for removing the first stack of labels fromthe fibre channel frame; and means for forwarding the fibre channelframe in-order to a second fibre channel device.
 9. The apparatus ofclaim 8, wherein the fibre channel frame is forwarded substantiallywithout any label information.
 10. The apparatus of claim 8, furthercomprising: inserting a second set of labels into the fibre channelframe.
 11. The apparatus of claim 8, wherein the first stack of labelscomprises of one or more labels.
 12. The apparatus of claim 11, whereinthe one or more of the labels are associated with one or more virtualstorage area networks.
 13. The apparatus of claim 8, wherein the firststack of labels is included in the Enhanced Interswitch Links (EISL)header.
 14. The apparatus of claim 8, wherein the first stack of labelsis included in the fibre channel frame header.
 15. A device, comprising:an interface operable to receive a fibre channel frame having a firststack of labels, the fibre channel frame received through a tunnel in aTransport Control Protocol/Internet Protocol (TCP/IP) network, wherein acontrol word in the fibre channel frame is used to reorder framesreceived out of order at the device to provide in order delivery; aprocessor operable to reordering frames, reference an entry in a labelinformation base based on the first stack of labels and remove the firststack of labels from the fibre channel frame; wherein the interface isfurther operable to forward the fibre channel frame in-order to a fibrechannel device.
 16. A computer readable storage medium having computercode embodied therein, the computer storage readable medium comprising:computer code for receiving a fibre channel frame having a first stackof labels at a first fibre channel device, the fibre channel framereceived through a tunnel in a Transport Control Protocol/InternetProtocol (TCP/IP) network, wherein a control word in the fibre channelframe is used to reorder frames received out of order at the first fibrechannel switch to provide in order delivery; computer code forreordering frames at the first fibre channel device; computer code forreferencing an entry in a label information base at the first fibrechannel device based on the first stack of labels; computer code forremoving the first stack of labels from the fibre channel frame; andcomputer code for forwarding the fibre channel frame in-order to asecond fibre channel device.